PROJECT SUMMARY Older adults are the fastest growing segment of the U.S. population. One challenge most adults will experience as they become older is difficulty in understanding what others say. This difficulty arises primarily due to age- related decline in hearing, one of the most prevalent chronic conditions in older adults. Declines in central auditory processing (e.g., temporal resolution) and in cognitive function further contribute to speech recognition problems. Successful communication is, however, essential to our lives, as it fosters social participation, which is pivotal to cognitive and physical health at all ages. The vast majority of research has focused on speech perception through listening only, thus failing to capture one of the most common experiences of communication in our lives, namely, speaking face-to-face. Speaking face-to-face provides a valuable strategy for aging adults to compensate for their age-related difficulties in auditory speech perception: Access to both auditory and visual speech typically leads to more robust recognition in all age groups. The mechanisms by which audiovisual information benefits speech recognition in aging adults remain, however, largely unknown. It is critically important to understand the mechanisms by which aging listeners benefit from audiovisual speech to maximize the extent to which they can compensate for deficits in auditory speech recognition and normalize the ability to communicate. Electrophysiological measures can provide direct indices of the effects of visual information on auditory perceptual processing that contribute to the observed behavioral benefits to speech recognition. The objective of this proposal is to understand the mechanisms by which older adults benefit from visual information during speech processing. The approach in our work is to use electrophysiological measures in younger, middle-aged, and older adults to define age-related differences in audiovisual processing. These measures will be compared to performance on speech recognition tasks to determine which are most directly related to successful communication. The inclusion of middle-aged listeners will allow identification of the onset of age-related changes, setting the basis for future investigations into early markers of different trajectories of aging. Further, we will determine individual characteristics in older adults that are predictive of the degree of benefit gained from visual speech. The findings will significantly advance our theoretical understanding of how listeners in different age groups benefit from visual information during real-time speech processing. The proposed research directly addresses an important problem facing us all ? how to maintain effective speech comprehension throughout aging. Greater understanding of the mechanisms by which audiovisual speech benefits comprehension at multiple stages in life is necessary to maximize the use of this established compensatory mechanism. The outcomes will set the basis for clinical assessments and interventions aimed at improving the use of audiovisual speech to achieve functional speech perception in aging. Better communication in older adults strengthens their social participation and increases potential for healthy aging.